[0001] This invention relates to a lock unit, and in particular to a lock unit of the type
that is used in association with a cylinder lock, and which has has improved security.
[0002] Lock units commonly installed in doors, particularly of the uPVC type, are commonly
used in association with a cylinder lock. Cylinder locks comprise an elongate barrel
that is accommodated in a channel within the lock unit, the barrel having a cam member
that is operated by a key inserted into the lock.
[0003] Customarily, when the cylinder lock is installed, the external end of the cylinder
lock barrel projects from the door. One method employed by criminals to break into
a property is to apply sufficient force to the projecting end of the cylinder lock
barrel to break the barrel and forcibly remove the cylinder lock from the lock unit.
The criminal is then able to access the interior of the lock unit, for instance using
the tip of a screwdriver, in order to operate the locking mechanism and open the door.
[0004] Clearly, there is an ongoing need for improvements to the security of such lock units,
which are effective to foil any attempt to gain unauthorised access by forced removal
of the cylinder lock. Generally, any measures that prolong the time necessary for
a forced entry to be effected contribute to the overall security of a lock system.
Industry standard performance tests, for instance, often require an installation to
withstand attack for a period of three minutes, it being considered that criminals
will generally not spend longer than that in attempting to break in to a property.
[0005] There has now been devised an improved lock unit which addresses this need, and which
overcomes or substantially mitigates the above-mentioned and/or other disadvantages
associated with the prior art.
[0006] According to a first aspect of the invention, there is provided a lock unit for installation
in a door or the like, the lock unit being for use in association with a cylinder
lock and including a channel within which the cylinder lock is, in use, received,
wherein the lock unit comprises a shutter element arranged to occlude the channel
in the event that the cylinder lock is forcibly removed therefrom.
[0007] The lock unit according to the invention is advantageous primarily in that the occlusion
of the channel by the shutter element in the event of forced removal of the cylinder
lock prevents or inhibits access to the interior of the lock unit. Consequently, even
if a criminal successfully removes the cylinder lock, he is unable to gain access
to the locking mechanism within the lock unit, as such access is blocked by the shutter
element.
[0008] In certain embodiments of the invention, the shutter element is a plate that is of
sufficient dimensions that it is capable of completely occluding the channel in which
the cylinder lock is received within the lock unit. The plate may be slidably mounted
within a groove or guide.
[0009] Commonly, the channel is defined by a pair of corresponding openings in opposite
faces of the lock unit. Typically, the openings are formed in opposite walls of the
casing of the lock unit, and are dimensioned such that they cylinder lock is closely
received within them. The shutter element is preferably disposed such it is aligned
flush with the internal surface of the casing, at the side of lock unit that, in use,
is towards the external side of the door.
[0010] The shutter element is preferably biased towards the position in which it occludes
the channel in the lock unit. In other words, in normal use the shutter element is
preferably prevented from occluding the channel by the presence of the cylinder lock,
removal of the cylinder lock causing the shutter element to move to its operative
position in which it occludes the channel. Biasing of the shutter element to its operative
position is preferably brought about by means of a resilient member that acts upon
the shutter element. Most conveniently, the resilient member is a spring, eg a compression
spring, which may act between the shutter element and the end of a groove or guide
within which the shutter element is slidably mounted.
[0011] Preferably, means are provided for restraining the shutter element in an inoperative
position, in which the channel in the lock unit is not occluded, for the purposes
of installation of the lock unit. Once the lock unit has been installed, and the cylinder
lock positioned within the channel, the shutter element is released so that it can
perform its function. The restraining means may comprise a pin mounted transverse
to the shutter element and which locates in a recess formed at the edge of the shutter
element. The tip of the pin and the recess in which it locates may be so shaped that
the pin can be removed from the recess, thereby releasing the shutter element, by
rotation of the pin. The restraining means may be re-engaged whenever it is desired
to remove the cylinder lock for legitimate purposes, eg replacement or maintenance.
[0012] To provide additional security, the shutter element may, in addition to occluding
the channel, also engage the locking mechanism within the lock unit, thereby further
inhibiting its operation. For instance, the leading edge of the shutter element may
be provided with a detent or other formation that engages a component of the locking
mechanism and prevents or restricts movement of it.
[0013] The lock unit may incorporate a locking mechanism of any suitable form. The invention
is applicable to any situation in which a cylinder lock is used, and in which forcible
removal of the cylinder lock from a channel in which it is accommodated would otherwise
provide access to the locking mechanism such that the lock could be unlocked.
[0014] Because doors may be hung at either the right-hand or left-hand edge, to suit the
requirements of the installation site, and because it is desirable that the shutter
element should be arranged adjacent the outward side of the lock unit, it is particularly
convenient for the lock unit to include two shutter elements, one at each side, so
that the lock unit is universal in that it is suitable for installation in doors that
are hung in either sense.
[0015] According to a second aspect of the invention, there is provided a lock assembly
comprising a lock unit including a channel within which a cylinder lock is received,
wherein the lock unit comprises a shutter element arranged to occlude the channel
in the event that the cylinder lock is forcibly removed therefrom.
[0016] In a further aspect of the invention, there is provided a door or the like in which
is installed a lock assembly comprising a lock unit including a channel within which
a cylinder lock is received, wherein the lock unit comprises a shutter element arranged
to occlude the channel in the event that the cylinder lock is forcibly removed therefrom.
[0017] Although described above primarily with reference to installation in doors, it will
be appreciated that the lock unit of the invention may be used in other forms of closure,
eg windows, hatches etc.
[0018] The invention will now be described in greater detail, by way of illustration only,
with reference to the accompanying drawings, in which
Figure 1 is a perspective view of lock unit incorporating a security device according
to the invention, in a locked operating condition, and showing a cylinder lock received
within the lock unit;
Figure 2 is a plan view, partly in section, of the lock unit of Figure 1, in the condition
in which it is supplied, prior to installation;
Figure 3 is a view similar to Figure 2, but showing the lock unit after installation
in a door, with the security device released;
Figure 4 is a perspective view of the lock unit in its normal operating condition,
when used to lock the door;
Figures 5 and 6 show the security device in the course of activation caused by removal
of a lock cylinder from the door; and
Figures 7 and 8 show the security device in a fully engaged condition following removal
of the lock cylinder from the door.
[0019] Referring first to Figure 1, a lock unit incorporating a security device according
to the present invention is generally designated 1. The lock unit 1 is, save for the
presence of the security device of the invention (which is described in detail below),
of the form described in
GB2455777A. Briefly summarised, the lock unit 1 includes a casing 10 that, together with a cover
plate 11 forms a substantially fully enclosed housing. The cover plate 11 is shown
only in Figure 1, so as to reveal the internal components of the lock unit 1 in the
other views. The lock unit 1 forms part of a multi-point locking system for a door,
and comprises a spring-loaded retractable latch 12 and a locking hook 14, both of
which are operated in a conventional manner by door handles mounted on spindles that
pass through one or both of square section bores 16,18 in two cam members 17,19. The
mechanism is further coupled to a drive bar 15, by which secondary locking units located
elsewhere on the edge of the door. Such secondary locking units may comprise locking
hooks, espagnolettes etc. In the embodiment illustrated, the lock unit 1 is installed
in the door with the cover plate of the housing disposed towards the external side
of the door.
[0020] Keyhole-shaped openings 29 in the casing 10 and the cover plate 11 define a channel
into which the barrel of a cylinder lock 5 can be inserted after the lock unit 1 has
been fitted to a door. Again, this is entirely conventional. The cylinder lock 5 is
shown only in Figure 1.
[0021] The cylinder lock 5 includes a cam member that acts on a displaceable carriage 22,
causing the carriage 22 to reciprocate between locked and unlocked positions. In all
the drawings, the carriage 22 is shown in the locked position (at the leftmost extent
of its travel, as viewed in the drawings). The carriage 22 is operably linked to the
latch 12 and locking hook 14 by means of a lever 24.
[0022] The manner in which the lock unit 1 is operated, and the manner in which the cylinder
lock is coupled to the latch 12 and locking hook 14 is entirely as described in
GB2455777A and is not pertinent to the present invention.
[0023] The present invention addresses a problem associated with lock units of the type
described in
GB2455777A and indeed all lock units comprising a cylinder lock coupled to a locking mechanism,
which is that the barrel of the cylinder lock may be relatively easy for a skilled
and determined criminal to remove. Successful removal of the cylinder lock barrel
may then permit the criminal to operate the lock mechanism, eg using a screwdriver
or other such implement, thereby to unlock the door.
[0024] The embodiment of the invention shown in the drawings differs from the lock unit
described in
GB2455777A in that the foot of the lock unit 1 is constituted by a shutter unit 30 comprising
a cast metal block 31 having a vertical (in use) groove 32 formed therein. The groove
32 carries a shutter plate 33. The lower end of the shutter plate 33 is formed with
a slot that serves as a mounting for a compression spring 35. The compression spring
35 acts between the shutter plate 33 and the lower end of the groove 32, so as to
urge the shutter plate 33 upwards.
[0025] One of the sides of the shutter plate 33 (the left hand side as viewed in the drawings)
is formed with two cutouts 36,38. The first cutout 36 has the form of a right-angled
triangle and is located adjacent the top edge of the shutter plate 33. The first cutout
36 cooperates with a spring-loaded restraining pin 37 that is mounted in a transverse
bore in the block 31 and which has a chamfered tip that engages in the first cutout
36 (see Figure 2) in such a way that the shutter plate 33 is retained in the position
shown in Figure 2.
[0026] The restraining pin 37 can be rotated by means of a thin gauge Allen key inserted
into a hole 38 at the end of the bore within which the pin 37 is mounted. After the
lock unit 1 has been installed in a door, and after the cylinder lock 5 has been inserted
in the channel defined by the openings 29, the pin 37 is rotated through 180°. The
resultant camming action of the abutting surfaces of the pin 37 and the first cutout
36 causes the pin 37 to be displaced from the first cutout 36 (see Figure 3). Consequently,
the upper end of the shutter plate 33 bears against the underside of the cylinder
lock 5.
[0027] If it is desired to remove the cylinder lock 5 for some legitimate purpose, eg maintenance
or replacement, the pin 37 is first rotated through 180° to the position shown in
Figure 2, so that removal of the cylinder lock 5 does not permit upward displacement
of the shutter plate 33.
[0028] In normal use, when the door is locked, the lock unit 1 has the configuration shown
in Figure 4. The locking hook 14 protrudes from the lock unit 1 and engages a keeper
on the door jamb. The latch 12 also protrudes into a keeper. Any secondary locking
units are similarly engaged with keepers on the door jamb. The carriage 22 occupies
the locked (leftmost) position.
[0029] To attempt to break open the door, a criminal may forcibly remove the cylinder lock
5. If it were not for the presence of the security device according to the invention,
this would provide access to the locking mechanism. In particular, the criminal may
be able to manipulate the carriage 22 and/or lever 24, for instance by inserting a
screwdriver through the opening 29 in the cover plate, in such a way that the mechanism
can be unlocked and the door opened, so that the criminal is able to gain access to
the property.
[0030] The security device of the present invention, however, prevents or severely inhibits
the ability of the criminal to gain access to the locking mechanism. As soon as the
cylinder lock 5 is forcibly removed, the shutter plate 33 is urged upwards by the
compression spring 35. The shutter plate 33 is aligned substantially flush with the
internal surface of the cover plate of the lock unit 1. Movement of the shutter plate
33 from its normal, resting position (see Figure 4) to the operative position shown
in Figures 7 and 8 (via the intermediate position of Figures 5 and 6) occurs very
rapidly. In the operative position (Figures 7 and 8), the shutter plate 33 occludes
the opening 29 in the cover plate and so blocks access to the interior of the lock
unit 1.
[0031] Access to the interior of the lock unit 1 is further prevented by engagement of the
pin 37 with the second cutout 38. Upward movement of the shutter plate 33 brings the
second cutout 38 into registration with the transverse bore in which the pin 37 is
accommodated, such that the pin 37 is pressed into the second cutout 38 by the action
of its associated compression spring. Engagement of the pin 37 in the second cutout
38 prevents the shutter plate 33 being prised downwards in such a way that might reopen
the opening 29 and so enable access to the lock mechanism.
[0032] The upper, leading edge of the shutter plate 33 is provided with an upstanding detent
39 which, when the shutter plate 33 is in its operative position engages behind part
of the carriage 22. This effectively maintains the lock mechanism in the fully locked
condition.
[0033] It will be appreciated that the illustrated embodiment is suitable for use in door
that is hung on the right (when viewed from the exterior), such that the cover plate
of the lock unit 1 and the shutter plate 33 are disposed at the external side of the
lock unit 1. For installation in a door hung in the opposite sense, an embodiment
in which the shutter plate 33 is disposed flush with the internal surface of the casing
10, rather than the cover plate, would be suitable. More conveniently, however, the
shutter unit 30 may contain two shutter plates, adjacent the two major faces of the
shutter unit 30, so that the unit is universal, being suitable for installation in
doors hung in either sense.
1. A lock unit for installation in a door of the like, the lock unit being for use in
association with a cylinder lock and including a channel within which the cylinder
lock is, in use, received, wherein the lock unit comprises a shutter element arranged
to occlude the channel in the event that the cylinder lock is forcibly removed therefrom.
2. A lock unit as claimed in Claim 1, wherein the shutter element is a plate that is
of sufficient dimensions that it is capable of completely occluding the channel in
which the cylinder lock is received within the lock unit.
3. A lock unit as claimed in any preceding claim, wherein the channel is defined by a
pair of corresponding openings in opposite faces of the lock unit.
4. A lock unit as claimed in any preceding claim, wherein the shutter element is disposed
such it is aligned flush with the internal surface of the lock unit, at the side of
lock unit that, in use, is towards the external side of the door.
5. A lock unit as claimed in any preceding claim, wherein the shutter element is biased
towards the position in which it occludes the channel in the lock unit.
6. A lock unit as claimed in Claim 5, wherein biasing of the shutter element to its operative
position is preferably brought about by means of a resilient member that acts upon
the shutter element.
7. A lock unit as claimed in Claim 6, wherein the resilient member is a compression spring.
8. A lock unit as claimed in any preceding claim, wherein means are provided for restraining
the shutter element in an inoperative position, in which the channel in the lock unit
is not occluded, for the purposes of installation of the lock unit.
9. A lock unit as claimed in Claim 8, wherein the restraining means comprises a pin mounted
transverse to the shutter element and which locates in a recess formed at the edge
of the shutter element.
10. A lock unit as claimed in Claim 9, wherein the tip of the pin and the recess in which
it locates are so shaped that the pin can be removed from the recess, thereby releasing
the shutter element, by rotation of the pin.
11. A lock unit as claimed in any preceding claim, wherein the shutter element, in addition
to occluding the channel, also engages the locking mechanism within the lock unit,
thereby further inhibiting its operation.
12. A lock unit as claimed in Claim 11, wherein the leading edge of the shutter element
is provided with a detent or other formation that engages a component of the locking
mechanism and prevents or restricts movement of it.
13. A lock unit as claimed in any preceding claim, which includes two shutter elements.
14. A lock assembly comprising a lock unit as claimed in any preceding claim and a cylinder
lock.
15. A door or the like in which is installed a lock assembly as claimed in Claim 14.